The 50-year-old All Nippon Airlines pilot has been grounded pending an internal probe ordered by industry regulators, company spokesman Kunio Shibata said Friday.

Shibata said the 80 passengers on the flight from Tokyo to the southwestern city of Ube were never in danger because the Boeing 767-300 was flying on autopilot at the time of the March 23 incident.

He called it “extremely regrettable” and said Japan’s second-largest airline was redoubling efforts to ensure safety.

According to the airline, the pilot started to doze off after the aircraft had reached its cruising altitude and the autopilot had been engaged. He roused after an official from the Transport Ministry on board for a routine inspection noticed and tapped the co-pilot on the shoulder.

The pilot, whose name has not been released, nodded off again a few minutes later, prompting the co-pilot to yell at him.

The airline is conducting an investigation into the incident ordered by the ministry to determine whether the pilot was negligent or is suffering from a sleeping disorder, Shibata said.